Analysis Of Membrane Folding And Deploying Process Based On Origami

With the development of human deep space exploration,membrane structure as a new structural form,has gradually become an interesting direction in the aerospace field due to its light weight,small folding volume and easy deployment compared to traditional rigid mechanical structures.At present,membrane structures are widely used in solar sails,large-aperture antennas,sunshades and space solar power generation systems.Aiming at the problem that the membrane structure is prone to creases during the folding and compacting process,the proxy model is used to replace the creases to introduce initial defects into the folded membrane to realize the study of the membrane deploying process.Based on the finite element method,the Z-folding and deploying process of the membrane is simulated.And the elastoplastic behavior of the crease is parameterized.The ABAQUS connector is used to replace the crease area of the membrane,the behavior of the connector simulates the elastoplastic characteristics of the crease to realize the establishment of the crease proxy model.Its effectiveness is verified by experiments.In order to study the kinematic relationship in folding and deploying process of the membrane,the membrane surface is assumed to be a rigid body except for the crease area,that is,the in-plane will not produce strain.Use the homogeneous coordinate transformation of the linkage mechanism to analyze the simplified Miura membrane.And the interaction relationship between the dihedral angles of the membrane surface is studied.The synchronization problem of the transverse and longitudinal displacements during the membrane deploying process is proposed.It also provides reference for the application of boundary conditions in the subsequent membrane deployment simulation.The deploying process of Miura membrane is simulated.The influence of force driving and constant-speed driving on the deploying process and results of the membrane is explored.Aiming at the self-contact phenomenon that occurs during the membrane deploying process at a constant-speed driving,a step-speed driving method is proposed according to the motion trajectory of the membrane corners under the force drive,so as to reduce the surface curvature during the membrane deploying process and achieve the purpose of solving its self-contact problem.In addition,the stability of the membrane deploying process is analyzed by comparing the changes in the deployment rate,deployment error and self-contact area during the membrane deploying process under different driving modes.Based on the finite element method,the deploying process of the multi-element Miura membrane is simulated.And the stretch ratio,maximum von Mises stress,deployment rate,wrinkle deformation,etc.of membrane structure are discussed.The existence of creases can cause damage to the membrane surface.The number of parallelogram elements and the longitudinal crease angle of the same size membrane is changed respectively.And the influence of the above two on the total crease length and storage volume of the folded membrane is studied.When the longitudinal crease angle is 15°,the transverse and longitudinal displacements of the folded membrane with different element numbers are not synchronized during the deploying process.By keeping the number of parallelogram elements constant,the longitudinal crease angle is changed.The influence of the longitudinal crease angle on the synchronization of the transverse and longitudinal displacements during the membrane deploying process is studied.The deployment experiment of Miura membrane is carried out.And the difference between the experiment and the finite element simulation in the transverse and longitudinal displacements of the membrane is analyzed.It is found that the finite element simulation error is within a reasonable range compared with the experiment,which verifies the reliability of the finite element simulation results.